DETERMINATION OF GA1-XALXAS EPITAXIAL LAYER COMPOSITION BY X-RAY-INTENSITY MEASUREMENTS OF QUASI-FORBIDDEN REFLECTIONS

A method of Al-content determination in Ga1-xAlxAs layers is proposed. It consists in X-ray diffraction investigation of integrated intensity of weak quasi-forbidden reflections. Their known property is utilized such that, due to the peculiarities of the structure factor, these reflections are sensitive to composition. Applicability of the method is demonstrated on results obtained for epitaxial Ga1-xAlxAs layers grown on (100) GaAs substrate by liquid phase electroepitaxy (LPEE). The choice of the most suitable reflection is discussed. It is shown that in general case the reflection 006, for which the influence of the defect structure on intensity is weak, should be applied rather than 002. The method is most useful in the range 0 < x < 0.4 where the estimated error, DELTAx, does not exceed 0.02.